Determining Left or Right in 2D space?

Question

Given point A (x,y) in 2D space, how do we know whether point B (a,b) in on the left side or right side of point A?

Answer 1

technically there is no left or right, unless you make some conventions or speak informaly

Answer 2

Just check x - a and y - b. If x - a is a + number, a is less than x and thus B is to the left of A. If x - a is a negative number, a is greater than x and thus B is to the right of A.

That is because by convention, + is to the right of the origin along the x - axis and - is to the left of the origin. Since the origin can be shiftedby a simple mathematical translation, it is clear that larger numbers are to the right and smaller numbers are to the left. Similarly, larger numbers are above and smaller numbers are below a given point (y coordinates).

Answer 3

Convention is that points are in (x,y) order. Thus if point B has an x-coordinate larger than that of A, it is to the "right", and vice versa.

Answer 4

One definition independent of the observer and where his eyes are might be this
x - a < 0 left;
x - a > 0 right